In recent years, in the microfabrication employed in production of a semiconductor device or a liquid crystal device, a progress has been seen in lithography technology; as a result, a rapid progress is taking place in fine pattern formation. As the means for fine pattern formation, a light of shorter wavelength is generally used for exposure; specifically, a conventional ultraviolet light represented by g-line or i-line is being changed to a DUV.
Currently, a lithography technology using a KrF excimer laser beam (248 nm) has been introduced into the market; a lithography technology using an ArF excimer laser bea m (193 nm) of even shorter wavelength is being introduced; and a lithography technology using a F2 excimer laser beam (157 nm) is under study as a next generation technology. Further, vigorous studies are under way on lithography technologies using an electron beam, an EUV, an X ray, an ion beam, etc., which are slightly different from the above technologies.
As a resist giving a high resolution to a light source of short wavelength or to an electron beam, an EUV, an X ray, an ion beam or the like, there was proposed “a chemically amplified resist” by IBM Co. Currently, improvements for this chemically amplified resist and developments of a new chemically amplified resist are being made actively.
Use of a light source of shorter wavelength has forced the structural change of the resin used in a resist. Therefore, in a lithography using a KrF excimer laser beam, there is used a polyhydroxystyrene showing high transparency to 248 nm, or a resin obtained by protecting the hydroxyl group of the polyhydroxystyrene with an acid-dissociable, dissolution-inhibiting group; in a lithography using an ArF excimer laser beam, attention is being paid to an acrylic resin transparent to 193 nm or a cycloolefin resin because the polyhydroxystyrene has insufficient transparency to 193 nm and is substantially unusable.
As the acrylic resin, there are mentioned those disclosed in JP-A 39665/92, JP-A 207069/98, etc.; as the cycloolefin resin, there are mentioned those disclosed in JP-A 153864/98, etc.
These resins, however, are still insufficient in performance, and a higher resolution and a good resist shape are needed. As the reason for low resolution and inferior resist shape, there is pointed out, for example, the deactivation of acid caused by the basic substance in air or the basic substance infiltrating from substrate. As a method for solving such a problem, it is known, for example, to add a basic compound in a KrF exciter laser beam lithography (JP-A 179300/97).
Currently; however, a resist of higher performance is required in industry. In an ArF laser beam lithography, in particular, a particular light source (wavelength) and a particular resin are used and a particular resolution is required; therefore, no effective additive has been found.